1. Field of the Invention
The present invention is related to the fields of molecular biology, virology, immunology and medicine. The invention provides a composition comprising an ordered and repetitive antigen or antigenic determinant array. The invention also provides a process for producing an antigen or antigenic determinant in an ordered and repetitive array. The ordered and repetitive antigen or antigenic determinant is useful in the production of vaccines for the treatment of infectious diseases, the treatment of allergies and as a pharmaccine to prevent or cure cancer and to efficiently induce self-specific immune responses, in particular antibody responses.
2. Background Art
WO 00/3227 describes compositions and processes for the production of ordered and repetitive antigen or antigenic determinant arrays. The compositions are useful for the production of vaccines for the prevention of infectious diseases, the treatment of allergies and the treatment of cancers. The compositions comprise a core particle, such as a virus or a virus-like particle, to which at least one antigen or one antigenic determinant, is associated by way of at least one non-peptide bond leading to the ordered and repetitive antigen array.
Virus-like particles (VLPs) are being exploited in the area of vaccine production because of both their structural properties and their non-infectious nature. VLPs are supermolecular structures built in a symmetric manner from many protein molecules of one or more types. They lack the viral genome and, therefore, are noninfectious. VLPs can often be produced in large quantities by heterologous expression and can be easily be purified.
Examples of VLPs include the capsid proteins of Hepatitis B virus (Ulrich, et al., Virus Res. 50:141–182 (1998)), measles virus (Warnes, et al., Gene 160:173–178 (1995)), Sindbis virus, rotavirus (U.S. Pat. No. 5,071,651 and U.S. Pat. No. 5,374,426), foot-and-mouth-disease virus (Twomey, et al., Vaccine 13:1603–1610, (1995)), Norwalk virus (Jiang, X., et al., Science 250:1580–1583 (1990); Matsui, S. M., et al., J. Clin. Invest. 87:1456–1461 (1991)), the retroviral GAG protein (WO 96/30523), the retrotransposon Ty protein p1, the surface protein of Hepatitis B virus (WO 92/11291) and human papilloma virus (WO 98/15631).
It is generally difficult to induce immune responses against self-molecules due to immunological tolerance. Specifically, lymphocytes with a specificity for self-molecules are usually hypo- or even unresponsive if triggered by conventional vaccination strategies.
The amyloid B peptide (Aβ1-42) has a central role in the neuropathology of Alzheimers disease. Region specific, extracellular accumulation of Aβ peptide is accompanied by microgliosis, cytoskeletal changes, dystrophic neuritis and synaptic loss. These pathological alterations are thought to be linked to the cognitive decline that defines the disease.
In a mouse model of Alzheimer disease, transgenic animals engineered to produce Aβ1-42 (PDAPP-mice), develop plaques and neuron damage in their brains. Recent work has shown immunization of young PDAPP-mice, using Aβ1-42, resulted in inhibition of plaque formation and associated dystrophic neuritis (Schenk, D. et al., Nature 400:173–77 (1999)).
Furthermore immunization of older PDAPP mice that had already developed AD-like neuropathologies, reduced the extent and progression of the neuropathologies. The immunization protocol for these studies was as follows; peptide was dissolved in aqueous buffer and mixed 1:1 with complete Freunds adjuvant (for primary dose) to give a peptide concentration of 100 μg/dose. Subsequent boosts used incomplete Freunds adjuvant. Mice received 11 immunizations over an 11 month period. Antibodies titres greater than 1:10 000 were achieved and maintained. Hence, immunization may be an effective prophylactic and therapeutic action against Alzheimer disease.
In another study, peripherally administered antibodies raised against Aβ1-42, were able to cross the blood-brain barrier, bind Aβ peptide, and induce clearance of pre-existing amyloid (Bard, F. et al., Nature Medicine 6:916–19 (2000)). This study utilized either polyclonal antibodies raised against Aβ1-42, or monoclonal antibodies raised against synthetic fragments derived from different regions of Aβ. Thus induction of antibodies can be considered as a potential therapeutic treatment for Alzheimer disease.
It is well established that the administration of purified proteins alone is usually not sufficient to elicit a strong immune response; isolated antigen generally must be given together with helper substances called adjuvants. Within these adjuvants, the administered antigen is protected against rapid degradation, and the adjuvant provides an extended release of a low level of antigen.
As indicated, one of the key events in Alzheimer's Disease (AD) is the deposition of amyloid as insoluble fibrous masses (amyloidogenesis) resulting in extracellular neuritic plaques and deposits around the walls of cerebral blood vessels (for review see Selkoe, D. J. (1999) Nature. 399, A23–31). The major constituent of the neuritic plaques and congophilic angiopathy is amyloid β (Aβ), although these deposits also contain other proteins such as glycosaminoglycans and apolipoproteins. Aβ is proteolytically cleaved from a much larger glycoprotein known as Amyloid Precursor Proteins (APPs), which comprises isoforms of 695–770 amino acids with a single hydrophobic transmembrane region. Aβ forms a group of peptides up to 43 amino acids in length showing considerable amino- and carboxy-terminal heterogeneity (truncation) as well as modifications (Roher, A. E., Palmer, K. C., Chau, V., & Ball, M. J. (1988) J. Cell Biol. 107, 2703–2716. Roher, A. E., Palmer, K. C., Yurewicz, E. C., Ball, M. J., & Greenberg, B. D. (1993) J. Neurochem. 61, 1916–1926). Prominent isoforms are A• 1–40 and 1–42. It has a high propensity to form 1-sheets aggregating into fibrils, which ultimately leads to the amyloid. Recent studies demonstrated that a vaccination-induced reduction in brain amyloid deposits resulted in cognitive improvements (Schenk, D., Barbour, R., Dunn, W., Gordon, G., Grajeda, H., Guido, T., Hu, K., Huang, J., Johnson-Wood, K., Khan, K., et al. (1999) Nature. 400, 173–177).
We have surprisingly found that self-molecules or self-antigens presented in a highly ordered and repetitive array were able to efficiently induce self-specific immune responses, in particular antibody responses. Moreover, such responses could even be induced in the absence of adjuvants that otherwise non-specifically activate antigen presenting cells and other immune cells.